1. Field of the Invention
The present invention relates generally to an image display device for displaying a color-printable image as a monochrome image in, e.g., a tape printing apparatus or a word processor, an electronic apparatus having the image display device, and an image display method for the image display device.
2. Description of Conventional Art
For image display devices of conventional color-printable electronic apparatuses of this type, monochrome liquid crystal display are often used in order to lower the prices of the apparatuses. When a color-printable image is displayed on such a monochrome liquid display, the image is displayed with white, black or gray on the basis of gradation (lightness). That is, when the gradation of the image has a value expressing a light color, the image is expressed with white or a gray close to white. On the other hand, when the graduation of the image has a value expressing a dark color, the image is expressed with black or a gray close to black.
Thus, when a color-printable image is displayed on a monochrome liquid crystal display, the image is displayed on the basis of only gradation regardless of color data concerning three colors (e.g., red, green and blue). For that reason, even if color data of an image of inputted characters (a character image) are different from color data of an image of a background (a background image) for the character image, when the gradation of the character image is the same as that of the background image, both images are displayed with the same light and shade. Therefore, the character image on the monochrome liquid crystal display is displayed so as to be buried in the background image, so that it is very difficult to distinguish the character image from the background image.
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide an image display device capable of easily and clearly distinguishing a character image from a background image even if a color-printable image is displayed as a monochrome image, an electronic apparatus having the image display device, and an image display method for the image display device.
In order to accomplish the aforementioned and other objects, according to one aspect of the present invention, an image display device comprises: means for displaying a color-printable background image and a color-printable character image superposed on the background image, as monochrome images; and gradation control means for assigning a first gradation and a second gradation to the non-coloring and coloring of an element of the background image, respectively, and assigning a third gradation and a fourth gradation to the non-coloring and coloring of an element of the character image, respectively, to display a composite image of the background image and the character image.
The gradation control means may set a display based on the first gradation to be a negative display, a display based on the second gradation to be a dark color display, a display based on the third gradation to be a positive display, and a display based on the fourth gradation to be a light color display.
Preferably, the gradation control means does not display a ground tint element of the character image regardless of the non-coloring or coloring of the ground tint element.
In addition, the gradation control means may alternatively display the composite image of the background image and the character image on an input screen with print image or an print image sole screen, and cause the assignment of the first through fourth graduations when the composite image of the background image and the character image is displayed on the input screen with print image, to be different from the assignment of the first through fourth graduations when the composite image of the back ground image and the character image is displayed on the print image sole screen, with respect to at least a part of display elements.
Moreover, the gradation control means may cause the assignment of the first through fourth graduations when the composite image of the background image and the character image is displayed on the input screen with print image, to be different from the assignment of the first through fourth graduations when the composite image of the back ground image and the character image is displayed on the print image sole screen, with respect to a ground tint element of the character image.
According to another aspect of the present invention, an electronic apparatus comprises the above described image display device, and printing means capable of color-printing a display result of the image display device.
According to a further aspect of the present invention, there is provided an image display method for displaying a color-printable background image and a color-printable character image superposed on the back ground image, as monochrome images, wherein a first gradation and a second gradation are assigned to the non-coloring and coloring of an element of the background image, respectively, and a third gradation and a fourth gradation are assigned to the non-coloring and coloring of an element of the character image, respectively, to display a composite image of the background image and the character image.